firstStringAtIndex method Null safety

  1. @override
String? firstStringAtIndex(
  1. int index
)
override

第一列选中字符串

Implementation

@override
String? firstStringAtIndex(int index) {
  // 防止数组越界异常
  if (index >= 0 && index < firstList.length) return firstList[index];
  return null;
}